High-resolution space-borne and ground-based SAR persistent scatterer interferometry for landslide monitoring
- Autores: Rubén Iglesias González
- Directores de la Tesis: Francisco Javier Fabregas Canovas (dir. tes.), Jordi Mallorqui (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2015
- Idioma: inglés
- Tribunal Calificador de la Tesis: Oscar Mora Sacristan (presid.), Antoni Broquetas Ibars (secret.), Gerardo Herrera García (voc.)
- Programa de doctorado: Programa de Doctorado en Teoría de la Señal y Comunicaciones por la Universidad Politécnica de Catalunya
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Every year, with the onset of spring rains and snow melting, landslides represent one of the major threats to human life and infrastructures in natural environments. In this context, different surveying techniques, such as inclinometers, extensometers, piezometers or Global Positioning System (GPS) networks, are typically employed to address landslide monitoring problem. Nonetheless, these conventional techniques present several limitations. They are labor, expensive and usually require skillful users to data interpretation. Moreover, they typically provide poor spatial sampling and coverage, which hinder the characterization of complex landslides. Finally, these techniques require the direct installation of devices over the landslide surface, which could be a complex task, sometimes impossible to fulfill, in hard-to-reach locations. During the last decade, Synthetic Aperture Radar (SAR) Interferometry (InSAR) techniques based on space-borne SAR sensors have matured to a widely used geodetic tool for the precise monitoring of complex displacement phenomena with millimetric accuracy. Concretely, the new family of X-band SAR sensors, like the German TerraSAR-X and TanDEM-X satellites or the Italian constellation Cosmo-Skymed, have led to a scientific breakthrough presenting a lower revisiting time (up to few days) and an improved spatial resolution (up to the meter), compared with their predecessors ERS-1/2, ENVISAT-ASAR or RADARSAT-1, which worked at C-band. The industry, research laboratories, and universities are developing flexible tools for displacement monitoring analysis by means of space-borne InSAR techniques, which are being adapted for its fully operational use and for its integration with conventional observations and predictive models. Contrarily, when a high flexibility in terms of revisiting-time is required, or the need to fit the sensor orientation to the specific characteristics of the area under study exists, the research activity of several groups has been addressed to the development of Ground-Based SAR (GB-SAR) sensors. Easy to deploy, and cheaper if compared with space-borne solutions, GB-SAR sensors are a potential alternative, ideal for the monitoring of small-scale areas. The high stability of the sensor platform, and its flexibility in terms of revisiting time, make these systems an excellent option to detect displacements with a high temporal resolution of up to few minutes. Despite all these clear advantages, SAR sensors based on both space-borne and ground-based platforms also present some limitations, especially, over vegetated scenarios in mountainous environments, where landslides typically occur. Whereas its performance over bare surfaces or rocky areas is satisfactory during snow-free seasons, severe limitations arise from temporal decorrelation over vegetated areas, due to layover and shadowing effects caused by SAR geometrical distortions, the presence of tropospheric atmospheric artifacts or when rapid displacements are faced. Finally, it must be taken into account that SAR sensors are only sensitive to the satellite-to-target component of displacement, which may notably differ from the real one. There is still some way to go in order to overcome all these limitations and convert InSAR techniques into fully operational tools, context in which this PhD Thesis has been developed. The main objective of this PhD Thesis is the development of advanced InSAR techniques for the monitoring of areas affected by landslides. Concretely, the performance of both space-borne and ground-based SAR sensors will be compared and evaluated in the area of El Forn de Canillo, Andorra, which corresponds to one of the biggest landslides of the Pyrenees. The techniques presented in this PhD Thesis provide evidences for informed decision making, supported by the science, in order to ease the management of the geo-hazard risk associated with active landslides.
